Evaluation of High-Density Polyethylene and Low-Density Polyethylene (Plastic) Degradation by Isolated Bacteria

Mok, Zi Xin (2019) Evaluation of High-Density Polyethylene and Low-Density Polyethylene (Plastic) Degradation by Isolated Bacteria. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

Text Mok Zi Xin_Full Text.pdf Restricted to Registered users only Download (911kB)

Abstract

Plastic is a synthetic polymer derived from petrochemicals and widely employed in wide range of applications. They are commonly applied due to their high durability and low cost, but the disposal of the plastic waste becomes a great challenge for solid waste management. These accumulated non-biodegradable plastics had emerged as a serious threat to our environment. Bacterial degradation as an environmental safe method to tackle the existing plastic waste. This project aims to evaluate the high-density polyethylene (HDPE) and low density polyethylene (LDPE) degradation by isolated bacteria B1. The bacteria B1 were cultured in carbon-depleting mineral salts medium supplemented the sterile HDPE or LDPE sheet and incubated shaken at 150 rpm for 10, 20, and 30 days at 30 oC. The percentage weight loss had resulted an increasing trend for both the HDPE and LDPE film with increasing 10 days of incubation period. The experimental data had indicated the isolated bacteria had utilise HDPE as the sole carbon source. Total protein of surface-attached B1 was estimated after 10, 20, and 30 days incubation period. Tetrazolium chloride (TTC) reduction assay was conducted to monitor the viability of B1 culture in the mineral salt medium. The mean absorbance plotted resulted a steadily increased trend with increasing incubation period indicated the cells viability. The experimental had evidenced B1 as a polyethylene degrading bacteria. Bacteria Adhesion to Hydrocarbon (BATH) assay had monitored the isolated bacteria hydrophobicity to non polar polyethylene by measuring absorbance of the aqueous bacterial suspension after phase separation. According to the outcomes,B1 was confirmed to be plastic-degrading bacteria. Biochemical tests were performed to identify the polyethylene degrading bacteria B1.